This Application relates to the U.S. Application Ser. No. 09/641,153 filed Aug. 17, 2000 entitled, xe2x80x9cWafer Container Having Electrically Conductive Kinematic Coupling Groove To Detect The Presence Of The Wafer Container On A Support Surface, The Support Surface, and Methodxe2x80x9d and assigned to Semiconductor 300 Gmbtt and Co., Infineon Technologies AG and Motorola, Inc.
This invention relates to carriers for semiconductor wafers, and more particularly, relates to a container for transporting and storing wafers.
In semiconductor industry, wafers have to be carefully carried between processing stations. Currently there is a trend to carry them in a container, such as, for example, in a Front Opening Unified Pod (FOUP).
FIG. 1 illustrates a simplified cross-section diagram of a conventional transportation system with FOUP 10 and support surface 20. FOUP 10 comprises slots to hold a plurality of wafers, robotic lifting flange 17 and manual lifting handles 16 for moving the FOUP.
FOUP 10 temporarily rests with its base plate 19 on support surface 20 of the processing equipment, such as a load port, a container shelf within a buffer or a stocker, or elsewhere. A transportation vehicle can also have such a support surface 20.
In order to align the position of FOUP 10 to the processing equipment with surface 20, kinematic coupling is used. A set of kinematic coupling grooves 11, 12 (only 2 of 3 shown) in the base plate 19 of FOUP 10 engages with kinematic coupling pins 21, 22 in support surface 20 (only 2 of 3 shown). Grooves 11, 12 settle over pins 21, 22 to establish points of mechanical contact. The dimension of the grooves and of the pins are standardized so that FOUPs of various suppliers are compatible with each other (SEMI E 57 xe2x80x9cMechanical Specification for Kinematic Couplings used to align and support 300-mm Wafer Carriersxe2x80x9d).
There are instances where the FOUP is not placed on the support surface as specified in the standard. Hence, there is a need to monitor the FOUP placement.